See my post yesterday, Razr M antennagate. It definitely has a weaker radio/antenna, at least compared to Razr Maxx. Just drops to 3G too often. Tried all over town. 20 db lower level than Razr Maxx. Unacceptable to me.
The 4.3" screen... not really. The android buttons are now part of it. Plus, I think, the Google search widget on the top of every home screen is not removable (it is on the Maxx). So you have about a 3.7" screen for Home screens and 4.0" for running apps. Sadly, it looks like pictures of the upcoming Razr HD do the same thing.
Another annoyance. You notice the usual Android settings button is not in the usual button row. You can still get at it several ways. When settings are required in an app, a settings button does pop up, but it isn't always in the same place. It is in that bottom row sometimes but not always.Very annoying.